1. Field of the Invention
The present invention relates to laboratory incubators, and more particularly, to a very small, inexpensive incubator having improved temperature stability, uniformity and temperature recovery response.
2. Description of the Prior Art
The temperature within a laboratory incubator must be maintained within a certain operating temperature range for specimen treatment and evaluation. Therefore, it is common to provide laboratory incubators with heating devices that are periodically cycled to maintain the interior temperature of the incubators in this range. Temperature control must be very precise, with less than 0.5xc2x0 C. variation desired in order to provide accurate, repeatable results.
Such stable temperature control is difficult to obtain with prior art incubators because they are typically large and hold numerous specimens. This presents a problem because the internal temperature of a large incubator varies from location to location within the incubator. In large incubators, temperature uniformity is poor, with actual individual sample exposure temperatures varying as much as 0.75xc2x0 C. between specimens in some incubators. Furthermore, when multiple specimens are placed in a large incubator, all the specimens are exposed to temperature variations each time the incubator is opened for access to any specimen. Further, large incubators are not energy efficient when one, or a small number of specimens must be incubated. And, of course, large incubators consume excessive laboratory space.
Accordingly, there is a need for an improved incubator that overcomes the limitations of the prior art.
The present invention addresses the above-described problems and provides a distinct advance in the art of microplate incubators. More particularly, the present invention provides an improved incubator that offers superior temperature uniformity and stability with a simple construction that reduces individual unit cost and allows for the efficient use of available space.
The incubator of the present invention broadly includes a housing having an enclosed incubation chamber therein; a heater positioned within the housing for heating the chamber; and a controller for regulating the operation of the heater to maintain the chamber at a desired temperature.
The incubator is optimally sized to hold a single standard microplate sample, providing less than 0.02 cubic feet of internal space. Such constrained size ensures the microplate sample is always in near proximity to the heater. The primary thermal path from the heater to the microplate is conductive and therefore more stable and uniform than the convection thermal path experienced by microplate samples in large incubators. The optimal sizing and conductive heat path also provide for improved temperature control when the chamber is accessed because less cooler ambient air can be admitted into the chamber.
In operation, the controller cycles the heater whenever the internal temperature is lower than the set operating temperature of the incubator, thus maintaining the operating temperature of the incubator within a desired range. The construction of the present invention provides improved temperature uniformity and temperature stability by shortening the thermal path between the heater and the specimen, reducing the distance between the heater and the temperature sensor and facilitating the operators"" ability to minimize access. The present invention more consistently and uniformly maintains the contained specimen microplate at the set temperature rather than, as in prior art incubators, allowing specimen microplate temperature to suffer temperature fluctuations based on random position and temperature variations within the incubator.
The incubator is configured to allow multiple incubators to be stacked vertically so as to provide efficient utilization of laboratory space. This allows laboratory personnel to establish multiple temperature controlled environments in a compact space.
The incubator also preferably includes an internal water reservoir that can be used to maintain a high humidity environment, reducing evaporation from the microplate sample. The operator can fill or replenish the reservoir externally.
A preferred embodiment of the invention couples a plurality of incubators together wherein secondary microplate incubator units may be electrically linked to a master incubator. The secondary microplate incubator units are simplified and less expensive because the temperature controller and sensor are not required. All units are maintained at the desired temperature based on the controller and sensor in the master incubator. A single control for multiple incubators also simplifies operation.
These and other important aspects of the present invention are described more fully in the detailed description below.